Image processing may include converting a line drawing to a corresponding rendered image. This conversion may be achieved using edge detection techniques, which may be used to find boundaries of objects by detecting discontinuities in brightness. In some instances, edge detection techniques may be for image segmentation and data extraction in areas such as image processing, computer vision, and machine vision. In some applications, the purpose of detecting the discontinuities in brightness may be to capture important events and changes in properties of the world. For example, discontinuities in brightness may be related to discontinuities in depth, discontinuities in surface orientation, changes in material properties, and/or variations in scene illumination. In some implementations, edge detection techniques treat edges of an object as an absolute truth, e.g., the rendered image is generated to look identical to the line drawing, thereby resulting in a rendered image having unwanted irregularities. However, these irregularities may be undesired in the rendered image. There is a need in the art, therefore, for methods and systems for converting a line drawing to a rendered image without undesired irregularities in the rendered image.